Embodiments of the present invention relate to a pump arrangement and in particular to a pump arrangement comprising a microfluidic pump and a safety valve arrangement at the pump outlet of the microfluidic pump. The safety valve arrangement may comprise a first safety valve for a free flow protection in a backward direction (with respect to the fluid pumping direction of the microfluidic pump) and, optionally, an additional second safety valve for a free flow protection in a forward direction of the microfluidic pump.
Known micropumps are problematic in that a free flow through the micropumps may take place when an overpressure or a positive pressure is applied to the inlet or outlet of the micropump and there is no operating voltage applied to the micropump. In order to avoid an uncontrolled flow through the micropump, a check valve may be respectively arranged at the inlet and the outlet of the micropump. However, in specific applications, which need a tight pump arrangement especially in the backward direction with respect to the pumping direction of the micropump, e.g. in (implantable) drug delivery systems or micropumps for tires, the backward free flow or leakage of the fluid has to be very low, for example 0.1 μl/hour. However, this is hardly achievable with conventional silicon check valves.
Moreover, micropump arrangements according to known technology are disadvantageous in that additional, separate components are needed which in turn results in increased space and cost requirements. Additionally, conventional pump arrangements exhibit a relatively large dead volume, wherein again fluidic fittings are needed.
Consequently, there is a demand for a pump arrangement in which an unwanted free flow in a backward direction (with respect to the pumping direction) or in both directions can be reliable prevented in an inactivated state of the micropump and which comprises a inexpensive design or setup and provides a small dead volume.